The present disclosure relates to the design of integrated circuits. More particularly, the present disclosure relates to methods for computing Miller-factors using coupled noise peak.
In electrical circuits, noise is an extraneous signal that can be capacitively coupled into a digital circuit from other parts of the system. One source of noise is a signal pickup from a changing voltage on another wire, such as a nearby logic signal wire, also known as a “net”, which connects two or more electronic circuit components.
In the design of electric circuits, such as semiconductor chip design, it can be important to verify the noise, which may be induced on a “victim” net of the chip by its neighboring “aggressor” nets. Specifically, the aggressor nets can cause speed changes in the victim nets when the aggressor net and the victim net switch in opposite directions.
The use of de-coupling factors, such as Miller-factors, have been proposed as a convenient method to reduce a highly coupled circuit to a simpler de-coupling circuit approximation. Specifically, a coupled victim net can be replaced with an uncoupled net by multiplying the coupling capacitances by a Miller-factor or k-factor and connecting the coupling capacitances to ground.
Static timing analyzers determine the Miller-factor as a function of slew rates and arrival times (AT's) as described in U.S. Pat. No. 6,615,395. Unfortunately, the static timing analysis does not account for the noise when computing the Miller-factor. Rather, the static timing analysis typically assumes that the Miller-factor is fixed at a maximum of 2 (or some user specified maximum value) for opposite direction switching or is fixed at 0 (or some user specified minimum value) for same direction switching. However, these fixed approximates have not proven accurate for sub-micron circuitry.
Accordingly, it has been determined that it would be advantageous to have improved methods of computing Miller-factors, which account for the coupled noise peak.